JPH06306278A - Polyamide resin composition and exterior structural element using the same - Google Patents

Abstract

PURPOSE:To obtain a polyamide composition useful for a field of exterior structural elements, etc., excellent in strength, rigidity and surface brightness of molded articles and further in a mold releasing property. CONSTITUTION:The polymide resin composition contains a polyamide consisting of (a) 30-55wt.% polyamide resin, (b) 45-70wt.% glass fiber and (c) 0.02-0.5 pts.wt. aliphatic carboxylic acid and/or its derivative based on 100 pts.wt. (a)+(c), and having >=180 deg.C and <=220 deg.C crystallization temperature from a molten state (Tc) and 20-40 solution viscosity in formic acid.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyamide resin composition which is excellent in strength and rigidity in actual use, glossiness on the surface of a molded article, and mold releasability at the time of injection molding, and the same. The present invention relates to exterior structural parts.

[0002]

2. Description of the Related Art Polyamide resins are excellent in mechanical properties such as tensile strength, bending strength and elastic modulus, and also have good heat resistance and chemical resistance. Therefore, they are used in many fields such as precision machine parts and structural parts. ing. Among them, glass fiber reinforced polyamide resin, excellent high strength not found in other resins,
Since it has high rigidity, it is often used for structural parts that require particularly high strength and rigidity.

In this glass fiber reinforced polyamide resin composition, the strength and rigidity can be increased by increasing the compounding amount of glass fiber, and in fact, a polyamide resin containing 60 wt% of glass fiber is used. However, generally, as the glass fiber content increases, the glass fibers are more likely to float on the surface of the molded article, and the gloss tends to deteriorate. Large structural parts are not only high strength and high rigidity,
Appearance is also an important property, so a material that satisfies all of these properties at the same time is required.

As a technique for solving this, for example,
(JP-A-4-77554) and JP-A-4-14923.
4) and the like, and by using a polyamide resin or composition having a specific crystallization temperature (Tc) and a polyamide resin composition having a specific molding fluidity, it is possible to obtain a molded product having a good appearance. It is disclosed. However, in the above technique, by increasing the glass fiber content, the molding shrinkage rate of the resin molded product becomes smaller, the molded product is less likely to be released from the mold, and the crystallization temperature (Tc) is lowered. By doing so, the crystallization of the molded product in the mold is delayed and the molded product is not released from the mold unless the cooling time during molding is sufficient. That is, there is a problem that the molding time cycle becomes long and the productivity deteriorates. Further, there is a problem in that the appearance cannot be improved depending on the mold design only by the method of increasing the melt fluidity of the resin composition, and conversely, drawing occurs during molding, which makes molding difficult.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a molding material which is excellent in strength, rigidity, luster and mold releasability. In particular, the exterior structural parts referred to in the present invention are often large-sized molded products, and since the cooling time is often the rate-determining molding time cycle, high strength,
A material having high rigidity, good gloss, and capable of releasing the molded product from the mold even if the cooling time is short is a particularly desired material.

[0006]

Means for Solving the Problems The present invention solves the above problems and has the following gist. The present invention includes (a) 30 to 55% by weight of polyamide resin and (b) glass fiber 45.
A polyamide resin composition comprising 0.02 to 0.5 parts by weight of an aliphatic carboxylic acid and / or a derivative thereof with respect to 100 parts by weight of (c) (a) + (b), Further, the temperature (Tc) when the polyamide resin is crystallized from a molten state is 180 ° C. or higher and 220 ° C. or lower, and the formic acid solution viscosity is 20 or higher and 40 or lower, and the above description. The gist of the invention is an exterior structural part made of the above polyamide resin composition.

The present invention will be described in detail below. The polyamide used in the present invention is a crystalline aliphatic polyamide,
Semi-aromatic polyamides, preferred polyamides are nylon 6, nylon 66/6 copolymer, nylon 66 / 6I copolymer, nylon 66 / 6T / 6I copolymer, or nylon 66 and those It is a blend polymer composed of at least two kinds of polymers selected from the above. Among these polyamides, in the resin composition, the peak value of heat of crystallization when the temperature was raised to 300 ° C. at 20 ° C./min in the resin composition, held for 3 min, and then lowered to 30 ° C. at 20 ° C./min ( Tc)
Is in the range of 180 ° C to 220 ° C, preferably 185 ° C
It is a polymer that enters 215 ° C. If the Tc of the polymer is higher than this range, the surface gloss of the molded product will be poor, and if it is too low, the releasability from the mold will be poor. Further, the viscosity of the polymer in this resin composition is a solution of formic acid (JIS K 681).
6) is a polymer of 20-40, preferably 22-38. If the formic acid solution viscosity of this polymer is higher than this range, the surface gloss of the molded product will be poor, and if it is too low, the molded product will be brittle.

The fiber diameter of the glass fiber used in the present invention is not particularly specified. For example, the fiber diameter is 10 to 13 μm,
Chopped strands having a fiber length of 3 to 6 mm may be used. The glass fiber content is 45 to 70 wt%, preferably 47 to 63 wt%. If the amount of glass fiber is larger than this range, not only the fluidity during molding deteriorates, but also
The surface gloss of the molded product becomes very poor, and if the amount is small, the strength and rigidity of the molded product are insufficient depending on the application, and a satisfactory structural part cannot be obtained.

The aliphatic carboxylic acid and / or its derivative used in the present invention is preferably an aliphatic carboxylic acid having 26 to 32 carbon atoms and / or its ester compound and / or
Alternatively, a metal salt of the aliphatic carboxylic acid, and among them, preferable are sodium montanate salt, calcium montanate salt, and montanic acid ester. The compounding amount is 0.02 to 0.5 with respect to 100 parts by weight of the polyamide resin composition.
Parts by weight, preferably 0.03 to 0.3 parts by weight. If the amount is less than 0.02 part by weight, the releasability is deteriorated,
Mold release will not occur unless the cooling time is long. This leads to a longer molding time cycle, that is, lower productivity. If it is more than 0.5 parts by weight, the polyamide resin composition is discolored.

The polyamide composition obtained by the present invention is excellent in strength, rigidity, and glossiness on the surface of a molded article, and is also excellent in mold releasability at the time of injection molding. Extremely useful. The exterior structural component referred to in the present invention is a mechanical component or a structural component that requires molded article surface workability (for example, high surface glossiness, texture processing, etc.) and requires relatively large strength and rigidity. For example, desk legs, chair legs, seats, cabins, furniture parts such as wagon parts, office equipment products such as laptop housings, door mirror stays, wheel rims, wheel caps, wipers, motor fans. , Seat lock parts, gears, automobile parts such as hot air blower housings, and other field products such as wheel rims, wheel spokes, saddles, saddle posts, handles, stands, bicycle parts such as luggage carriers, valve housings, nails, screws, bolts, For example, bolts and nuts. Among them, nylon 66/6 copolymer, nylon 66 / 6I copolymer, nylon 66 / 6T
/ 6I copolymer, nylon 66, nylon 6,
Suitable as the exterior structural component is a blend polymer composed of at least two kinds of polymers selected from nylon 66/6 copolymer, nylon 66 / 6I copolymer and nylon 66 / 6T / 6I copolymer. is there.

The polyamide resin used in the present invention, the glass fiber, the aliphatic carboxylic acid and / or its derivative are
Compounding using a normal single-screw or twin-screw extruder, compounding a polyamide resin and glass fiber, and then adding an aliphatic carboxylic acid and / or a derivative thereof to the outside of the pellet by a known blender or the like, or It is also possible to obtain a polyamide resin containing a concentration of an aliphatic carboxylic acid and / or a derivative thereof by blending it into the composition during injection molding.

A heat stabilizer, an antioxidant, a flame retardant, a lubricant, a release agent, a nucleating agent, a pigment, a dye, etc. may be added within a range not impairing the object of the present invention, and in some cases,
It may be blended with other polyamide resin or other resin.

[0013]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The scope of the present invention is not limited to the examples. The evaluations in Examples and Comparative Examples were performed by the following methods.

Crystallization temperature (Tc): Measurement was carried out using DSC-7 manufactured by Perkin Elmer. N ₂ flow rate 0.03
Liter / mim, resin composition amount (pellet amount) 10.
0 ± 0.5mg, 300 at 30 ℃ to 20 ℃ / min
After raising the temperature to ℃ for 3 min and holding, 20 ℃ / mi
The value of the crystallization heat quantity peak when the temperature was lowered to 30 ° C. with n.

Viscosity of formic acid solution: The GF in the resin composition was removed by filtration, and then the polymer was recovered according to JIS K6810.

Strength characteristics: Substituting tensile characteristics for ASTM
It carried out according to D638.

Rigidity property: Bending property is substituted, and ASTM
It carried out according to D790.

Gloss: Evaluation is 130 mm × 130 mm
A flat plate molded product having a thickness of 3 mm and a gate size of 3 mm × 6 mm is manufactured by a Toshiba IS150E injection molding machine, a cylinder temperature of 2
90 ° C, mold temperature 90 ° C, injection / cooling cycle 10/2
Molded under the molding conditions of 0 second, injection pressure of 350 kg / cm ² and injection speed of 50%, and the surface of the obtained molded product is JIS K
The glossiness measured according to 7105 was used.

Releasability: Molding was carried out under the following molding conditions using a mold equipped with the mold-releasing force measuring device shown in FIG.
The average release force from the 35th shot to the 35th shot was measured.

(Molding conditions) Injection molding machine: IS90B mold made by Toshiba Machine: Molded cup (1 piece) Cylinder temperature: 290 ° C Flat mold temperature: 80 ° C Injection pressure: 400kg / cm ² Injection time: 7sec Cooling time: 20 sec Example 1 90w equimolar salt of adipic acid and hexamethylenediamine
Nylon 66/6 copolymer obtained by usual melt polymerization of t% and ε-caprolactam 10 wt% (formic acid solution viscosity 3
5) and glass fiber (03JA manufactured by Asahi Fiber Glass Co., Ltd.
416) was melt-kneaded under the following conditions using a twin-screw extruder (PCM45 manufactured by Ikegai Tekko KK). Set the cylinder temperature of the twin-screw extruder to 290 ° C and set the screw rotation speed to 150.
Polymer was charged from the hopper at rpm. The glass fiber was added by side feed from C5 (Zone 5) so that the glass fiber content of the resin composition was 50 wt%. The polymer charging part and the glass fiber charging part are sufficiently N ₂
Purged. Vent vacuum was applied from C7 (Zone 7) (300 mmHg). The discharge rate was 35 kg / hr and the resin temperature was 302 ° C. Sodium montanate as a releasing agent was added to the thus obtained product (Hosst manufactured by Hoechst Japan Ltd.
0.13 parts by weight of talub NaW-1) was blended using a known blender to obtain pellets.

Example 2 Nylon 66 (Leona 1200 formic acid solution viscosity 35 manufactured by Asahi Kasei Corp.) and nylon 6 obtained by usual melt polymerization of ε-caprolactam were blended in a ratio of 70:30, and used in Example 1. The same amount of the same glass fiber was compounded in the same manner as in Example 1, and the same amount of sodium montanate salt was blended in the same manner as in Example 1 to obtain pellets.

Example 3 The same method as in Example 1 was applied to the blend of nylon 66 used in Example 3 and nylon 6 used in Example 2 in a ratio of 50:50, and the glass fiber used in Example 1. The amounts were compounded, and the same amount of sodium montanate salt was blended in the same manner as in Example 1 to obtain pellets.

Example 4 Nylon 66/6 copolymer used in Example 1 and Example 2
80% to 20 blended nylon 6 used in Example 1 and the same amount of glass fiber used in Example 1 were compounded in the same manner as in Example 1, and the same amount of montanic acid was prepared in the same manner as in Example 1. The sodium salt was blended to obtain pellets.

Example 5 Nylon 66/6 copolymer used in Example 1 and Example 1
The glass fiber used in Example 1 was compounded in the same manner as in Example 1 so that the glass fiber content was 55 wt%,
The same montanic acid sodium salt as in Example 1 was blended in the same amount as in Example 1 to obtain pellets.

Example 6 Nylon 66/6 copolymer used in Example 1 and Example 1
The glass fiber used in Example 1 was compounded in the same manner as in Example 1 so that the glass fiber content was 60 wt%,
The same montanic acid sodium salt as in Example 1 was blended in the same amount as in Example 1 to obtain pellets.

Example 7 80w equimolar salt of adipic acid and hexamethylenediamine
t%, nylon 66 / 6I copolymer obtained by ordinary melt polymerization of 20 wt% of equimolar salt of isophthalic acid and hexamethylenediamine, and the glass fiber used in Example 1 were used in the same manner as in Example 1. Example 1 compounding the same amount
The same amount of sodium montanate salt was blended in the same manner as above to obtain pellets.

Comparative Example 1 Nylon 66 and glass fiber were compounded in the same amount as in Example 1 and the same amount of sodium montanate salt was blended to obtain pellets. Comparative Example 2 Nylon 66/6 Copolymer (9
0/10) and glass fibers were compounded in the same amount as in Example 1 and the same amount of sodium montanate salt was blended to obtain pellets.

Comparative Example 3 Nylon 66/6 Copolymer (9
0/10) and glass fibers were compounded in the same amount as in Example 1 and the same amount of sodium montanate salt was blended to obtain pellets.

Comparative Example 4 Nylon 66/6 copolymer (90/10) and glass fiber were used in the same manner as in Example 1 to obtain a glass fiber content of 33 wt.
%, And the same amount of sodium montanate salt as in Example 1 was blended to obtain pellets.

Comparative Example 5 Nylon 66/6 copolymer (90/10) and glass fiber were used in the same manner as in Example 1 to give a glass fiber content of 75 wt.
% So that the same amount of sodium montanate salt as in Example 1 was blended to obtain pellets.

Comparative Example 6 Nylon 66/6 copolymer (90/10) and glass fiber were compounded in the same manner as in Example 1, but sodium montanate salt was not added. Comparative Example 7 Nylon 66/6 copolymer (90/10) and glass fiber were compounded in the same manner as in Example 1, and 1.0 wt% of montanic acid sodium salt was blended to obtain pellets.

Comparative Example 8 Nylon 6 (formic acid solution viscosity: 39) obtained by ordinary melt polymerization of ε-caprolactam and the glass fiber used in Example 1 were compounded in the same amount in the same manner as in Example 1, The same amount of sodium montanate salt as in Example 1 was blended in the same manner as in Example 1 to obtain pellets. Examples 1 to 7 above
The results of Comparative Examples 1 to 8 are shown in Tables 1 and 2 below.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

According to the present invention, the strength under actual use,
It is possible to provide a polyamide resin composition that is excellent in rigidity and gloss on the surface of a molded product, and is also excellent in mold releasability during injection molding, and is very suitable as a structural component for exterior.

[Brief description of drawings]

FIG. 1 is a schematic view of a mold having a releasing force measuring device used when measuring the releasing force according to the present invention.

[Explanation of symbols]

 1 Nozzle of injection molding machine 2 Sprue runner 3 Molded product (cup shape) 4 Ejector pin 5 Ejector plate 6 Pressure sensor 7 Knockout rod 8 Cavity 9 Core 10 Releasing force recorder

Claims (3)

[Claims] 1. (a) 30 to 55% by weight of polyamide resin, (b) 45 to 70% by weight of glass fiber, (c) and (a).
+ (B) A polyamide resin composition comprising 0.02 to 0.5 part by weight of an aliphatic carboxylic acid and / or a derivative thereof with respect to 100 parts by weight, and the polyamide resin is crystallized from a molten state. The temperature (Tc) when doing is 180
℃ or more and 220 ℃ or less, and formic acid solution viscosity is 20
The polyamide resin composition of 40 or more and 40 or less. 2. An exterior structural part comprising the polyamide resin composition according to claim 1. 3. The polyamide resin is a copolymer of nylon 66 and nylon 6 (hereinafter, nylon 66/6 copolymer), a copolymer of nylon 66 and hexamethylene isophthalamide (hereinafter, nylon 66 / 6I copolymer). Or a copolymer of nylon 66, hexamethylene terephthalamide and hexamethylene isophthalamide (hereinafter, nylon 66 / 6T / 6I copolymer), or nylon 66, nylon 66/6 copolymer, nylon 66 / 6I
The exterior structural part according to claim 2, which is a blend polymer composed of at least two kinds of polymers selected from a copolymer and a nylon 66 / 6T / 6I copolymer.